Recently, the data transfer rate over a wireless communication network is rapidly increasing. This results from the appearance and spread of a variety of devices, such as smart phones and tablet PCs which require Machine-to-Machine (M2M) communication and a high data transfer rate. Carrier Aggregation (CA) technology in which more frequency bands are efficiently used in order to meet a higher data transfer rate, Cognitive Radio (CR) technology, multiple antenna technology in which a data capacity is increased within a limited frequency, multiple base station cooperation technology, etc. are recently highlighted.
Furthermore, a wireless communication network is evolving into an increase in the density of accessible nodes around a user. Here, the nodes mean antennas or a group of antennas which are spaced apart from one another at specific intervals. However, the node is not limited to this sense, but can be used as a broader sense. That is, the node can become a pico eNB (PeNB), a home eNB (HeNB), a Remote Radio Head (RRH), a Remote Radio Unit (RRU), a relay, or distributed antennas (or group). A wireless communication system including nodes having a high density can have higher system performance through cooperation between the nodes. That is, if the transmission and reception of nodes are managed by one control station and thus the nodes operates like antennas or a group of antennas for one cell, the nodes can have more excellent system performance as compared with a case where the nodes operate as independent base stations. A wireless communication system including a plurality of nodes is hereinafter referred to as a multi-node system. If each node forming a multi-node system is an antenna, this is called a Distributed Antenna System (DAS).
In a multi-node system, each node may use its own cell identifier (ID) different from an eNB or may use the same cell ID as an eNB. If each node has its own cell ID and performs scheduling and handover, this multi-node system can be considered as a multi-cell system. In a multi-cell system, if cells (i.e., the coverages of nodes) are overlaid with each other, this multi-cell system is referred to as a multi-tier network.
In an existing wireless communication system, antennas are concentrically deployed in a base station that provides service to a specific geographical area. This wireless communication system is a called a Centralized Antenna System (CAS). If a multi-node system is introduced in such a way as to add nodes to an existing wireless communication system, how resources will be allocated to each node according to what method is problematic.